User Manual

SCSI Commands Reference Manual, Rev. J 112
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
An application client may request any one or all of the supported mode pages from the device server. If an application client
issues a MODE SENSE command with a page code or subpage code value not implemented by the logical unit, the command
shall be terminated with CHECK CONDITION status, with the sense key set to ILLEGAL REQUEST, and the additional sense code
set to INVALID FIELD IN CDB.
If an application client requests all supported mode pages, the device server shall return the supported pages in ascending page
code order beginning with mode page 01h. If mode page 00h is implemented, the device server shall return mode page 00h
after all other mode pages have been returned.
If the PC field and the PAGE CODE field are both set to zero, the device server should return a mode parameter header and block
descriptor, if applicable.
The mode parameter list for direct access devices for MODE SELECT and MODE SENSE is defined in 5.3. Parts of the mode
parameter list are specifically defined for each device type. Definitions for the parts of each mode parameter list that are unique
for each device-type may be found in the applicable command standards.
3.11.1.1 Current values
A PC field value of 00b requests that the device server return the current values of the mode parameters. The current values
returned are:
a) The current values of the mode parameters established by the last successful MODE SELECT command;
b) The saved values of the mode parameters if a MODE SELECT command has not successfully completed since the mode
parameters were restored to their saved values (see 3.7); or
c) The default values of the mode parameters if a MODE SELECT command has not successfully completed since the mode
parameters were restored to their default values (see 3.7).
3.11.1.2 Changeable values
A PC field value of 01b requests that the device server return a mask denoting those mode parameters that are changeable. In
the mask, the bits in the fields of the mode parameters that are changeable all shall be set to one and the bits in the fields of the
mode parameters that are non-changeable (i.e., defined by the logical unit) all shall be set to zero.
If the logical unit does not implement changeable parameters mode pages and the device server receives a MODE SENSE
command with 01b in the PC field, then the command shall be terminated with CHECK CONDITION status, with the sense key set
to ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN CDB.
An attempt to change a non-changeable mode parameter using the MODE SELECT command shall result in an error condition
(see 3.7).
The application client should issue a MODE SENSE command with the PC field set to 01b and the PAGE CODE field set to 3Fh to
determine which mode pages are supported, which mode parameters within the mode pages are changeable, and the
supported length of each mode page prior to issuing any MODE SELECT commands.